OK, I have a dumb question. When I bought my truck, I noticed manual locking hubs on the sticker. After inspection, you turn the hubs one direction and it's on AUTO. The other way says LOCKED. If it's automatic, what's the point of having a manual lock option???

I had Ford auto-lock hubs go out multiple times. The worst is when it breaks while lockeds in and won't release. You can't drive like that on pavement to get home without trashing a drivetrain, so it has to go on a flatbed. I also had them fail to lock IN as well. I've not had a 4x4 Chevy, so can't speak to their track record.

the locking hubs is to lock the axle to the hub. when the hubs are unlocked it does not turn the ring and pinion or the driveshaft. this reduces wear on the drive train. when the hub is locked it allows the axle to drive the hubs or the front wheels. the only bad thing about manual hubs is you have to get out and lock them or you have no front axle drive.

Four wheel drive hubs have come a long way since the first auto lock hubs, which were somewhat troublesome. My 1983 K30 had auto locks from the factory, and like a box of chocolates, you never knew what you would get when you shifted in and out of 4wd. Those early one like that were the ones that had a little spring clutch setup in them, and you drove either forward or backward after shifting them to engage them. When disengaging, you shifted, then drove the opposite direction to unlock them. This is where the problems usually happened, and one or both would not un lock. If just a little bit of the wrong grease got in the wrong place, the hub would stick, and not unlock. The newer autos are pretty reliable, and most use a vacuum to engage. The manual position will override the auto in the event the auto fails. My last three trucks had these, and they have always worked. The older ones are easily converted to manual hubs, and it is well worth it.

Boss has about 360k miles on his f250 with manual hubs. In the 7 years that I've worked with him we have had to use the manual lock 2 times on the job and he had the whole system professionally rebuilt after the first time.